The present invention relates generally to seals and more particular to nested seals for use in surgical access ports, commonly referred to as trocars.
Instrument seals generally comprise a septum seal that is sized and configured to work within a specified range of instrument diameters, e.g., from 5 mm to 12 mm. This range requires that the orifice of the instrument seal stretch to accommodate the largest instruments. However, it must also seal around the outer diameter of the smallest instruments when they are inserted therethrough and while they are manipulated within a working channel that accommodates the largest instruments. The side-to-side or off-axis motion of the smaller instruments within the large working channel may create leakage as the orifice is deformed by the inserted instrument.
To deal with this challenge, instrument seals that float in response to the motion of an inserted instrument so that the orifice may be sized to the instruments accurately were developed. The floatation of the seal removes orifice deformation caused by the motion of an inserted instrument. Instead, the orifice is encouraged to follow the motion of the inserted instrument. However, there remains a need to continue to expand the useful range of instrument seals in surgical access devices even further. For instance, an instrument range between 3 mm and 16 mm is presently a developing requirement. This range may exceed the elastic properties of materials that are appropriate for such instrument seals.